Motor neuron disease mortality rates in U.S. states are associated with well water use

Figures & data

Table I. Descriptive data and correlations of independent variables and age-adjusted death rates per 100,000 people.

	Radon score	% White	% Wells	% Rural	% Smoke
	Mean (S.D.)	Mean (S.D.)	Mean (S.D.)	Mean (S.D.)	Mean (S.D.)
Total	0.359 (0.133)	0.806 (0.128)	0.176 (0.099)	0.265 (0.145)	0.415 (0.047)
	Correlation (p)	Correlation (p)	Correlation (p)	Correlation (p)	Correlation (p)
% White	0.600 (<.001)
% Wells	0.116 (0.438)	0.268 (0.069)
% Rural	0.179 (0.230)	0.314 (0.031)	0.621 (<.001)
% Smoke	0.082 (0.584)	0.210 (0.156)	0.511 (<.001)	0.696 (<0.001)
	MND Death Rate	MND Death Rate Males	MND Death Rate Females
	Mean (S.D.)	Mean (S.D.)	Mean (S.D.)
Total	2.106 (0.340)	2.544 (0.395)	1.744 (.302)
	Correlation (p)	Correlation (p)	Correlation (p)
Radon score	0.421 (0.003)	0.419 (0.003)	0.407 (0.005)
% White	0.702 (<.001)	0.661 (<.001)	0.702 (<.001)
% Wells	0.400 (0.005)	0.378 (0.009)	0.401 (0.005)
% Rural	0.379 (0.009)	0.382 (0.008)	0.360 (0.013)
% Smoke	0.174 (0.241)	0.169 (0.256)	0.170 (0.254)

Figure 1. Original (A) and reduced structural equation models (B) predicting MND death rates. Significant paths are solid lines. Prediction paths are straight arrows and covariances are curved double arrows.

Table II. Standardized coefficients from structural equation models predicting MND death rates.

	Original model†			Reduced model
Path	Estimate	S.E.	t	Estimate	S.E	t
Radon score	0.004	0.124	0.035
Race	0.630	0.112	5.63**	1.709	2.67	6.41**
Wells	0.222	0.128	1.74	0.783	0.342	2.29*
Rural	0.184	0.153	1.20
Smoking	−0.202	0.139	−1.45
Covariance
Radon Score*Race	0.583	0.096	6.08**	0.010	0.003	3.49**
Race*Wells	0.127	0.103	1.23
Race*Rural	0.106	0.087	1.22
Wells*Rural	0.607	0.092	6.57**	0.009	0.002	3.58**
Wells*Smoking	0.487	0.111	4.39**	0.002	0.001	3.08**
Rural*Smoking	0.682	0.078	8.73**	0.005	0.001	3.88**
Model Fit	Chi-square, 4 = 3.64, p =0.458 GFI =0.975; AGFI =0.867; RMSE =0			Chi-Square, 9 = 7.83, p =0.552 GFI =0.949; AGFI =0.880; RMSE =0
Path	Males			Females
Race	1.867	0.329	5.68**	1.520	0.237	6.42**
Wells	0.858	0.422	2.03*	0.698	0.304	2.30 *
Model Fit	Chi-Square, 9 = 8.15, p =0.519 GFI =0.946; AGFI =0.875; RMSE =0.			Chi-Square, 9 = 7.40, p =0.560 GFI =0.951; AGFI =0.887; RMSE =0.

*p < 0.05; **p<0.01

† Model estimating direct prediction coefficients between all independent variables and death rate and covariances of all pairs of independent variables with significant correlations from Table I. Covariance data for the independent variables is not repeated since it is unchanged for all reduced models.